WARNING: This article was written under the influence of caffeine.
For graduate students and those of us working in healthcare and biotech, caffeine often becomes a part of our daily schedule. Many of us become dependent on it for productivity, mood supplementation, and social interaction. The question becomes, will all of this coffee consumption hurt us in the long run?
Coffee and tea have been consumed for hundreds of years and are principle components of a variety of cultural and social traditions. In the United States, roughly 85% of adults consume coffee everyday. The cardinal ingredient in coffee is of course, caffeine. That beautiful, amazing chemical is named 1,3,7-trimethylxanthine, meaning there are 3 methyl groups at positions 1, 3, and 7 respectively. The average caffeine intake in the United States is roughly 135mg per day, which is equivalent to about 1.5 cups of home brewed coffee. Notably, coffee purchased at coffee shops tends to have more caffeine per cup with 16-20mg per fluid oz versus 11.5mg per fluid oz at home. For example, the nitro cold brew at Starbucks, which is one of my favorite drinks, has 280mg of caffeine in a 16oz serving! That's roughly equivalent to 3 cups of home brewed coffee in one drink and consistently outranks standard energy drinks.
The historical health concerns with coffee have been cardiovascular disease and cancer. Let's start with cardiovascular disease. I want to make clear that most of this information comes from epidemiologic studies, which are not capable of proving causation.
High blood pressure has always been a concern with coffee, and really any caffeinated beverage. With high blood pressure being so common, it's a reasonable concern! However, multiple meta-anaylsis and systematic reviews have concluded that caffeinated coffee consumption is not associated with increased risk of hypertension, increased blood pressure in healthy adults, or increased blood pressure in those who already have hypertension. As for other diseases like coronary artery disease (CAD) and stroke, up to 6 cups of filtered coffee per day was not associated with increased risk when compared to no coffee consumption. In fact, coffee consumption was associated with decreased risk of stroke and CAD with the lowest risk group being consumers of 3-5 cups per day (again, this is epidemiologic data, so take it with a grain of salt).
As for other other concerns such as obesity, insulin resistance, and diabetes, coffee once again comes out clean. Coffee can act as an appetite suppressant and sympathetic nervous system stimulant which often results in increased calorie expenditure and decreased calorie consumption. This can potentially help with weight loss, assuming you aren't loading you coffee with extra calories in the form of cream and sugar. In the short term, coffee can decrease insulin sensitivity, but that affect disappears over time with consumers of 5-6 cups per day over 6 months not having any change in their insulin sensitivity. This may be a result of tolerance to the adverse effects of coffee over time. In fact, other studies have associated habitual coffee consumption with a decreased risk of type-2 diabetes!
***Cough, cough, this is still epidemiology.
Lastly, let's touch on cancer. Many studies have shown that there is no association between coffee intake and cancer. On the contrary, coffee consumption was associated with a decreased risk of cancer, especially endometrial cancer and hepatocellular carcinoma. So there's really nothing to be worried about here so far as I can tell.
The last thing I want to touch on is dose. Just like anything, including water, whether or not something is harmful depends on how much you take. When it comes to caffeine, the general recommendation is to have no more than 400mg per day as a healthy adult and no more than 200mg per day if you're a pregnant or lactating female (sorry ladies). Hopefully that isn't too much of a challenge for you! This will help with preventing adverse effects from caffeine like anxiety, jitters, and headaches. All in all, moderate coffee intake can definitely be part of a healthy lifestyle and it's certainly a part of mine. Speaking of which, I'm off to get a cup. Cheers.